- 學位論文
具有高功率因數與頻閃補償之LED驅動器研製
LED Driver Development with High Power Factor and Flicker Compensation
摘要
本論文主要在研製一具有高功率因數與頻閃補償之驅動電源於LED照明應用。此電路由升壓型轉換器及降壓型轉換器組成，在升壓型轉換器採用開關元件之固定導通時間及配合高頻電感的零電流切換設計，使高頻電感操作於邊界導通模式，電源輸入電流將自動追隨輸入電壓，以提高電源側的功率因數，諧波含量亦符合歐盟所要求的EN61000-3-2 Class C諧波含量限制；在LED驅動電路採用降壓型轉換器之脈波寬度調變技術，以控制通過LED之平均電流，達到頻閃補償之目的，並利用電感電流平均控制技術原理，使LED驅動電源能應用於寬廣的LED電壓範圍，仍可獲得精確的LED定電流；同時採用虛接地式架構使積體電路能直接驅動開關元件，達到電路的精簡。最後將本論文電源系統整合後並量測光源結果，實驗結果證實雙級電源可有效抑制來自市電線電壓的低頻電流漣波所造成的頻閃問題，進而改善了照明的品質，並提升電路功率因數。
並列摘要
The major topic of this thesis is researching and developing a high-power factor and flicker compensation LED driver. The driver contains the first state, boost converter and the second stage, buck converter. We use the fixed-on time principle and combine with zero current detector control of high frequency inductor in the boost converter. The high frequency inductor can be operated at transition mode to make input current automatically following the input voltage for high power factor. The harmonics is conformed to the Europe standard of EN61000-3-2 Class C limit. On the other hand, the pulse-width modulation technique is used in the buck converter of the LED driver to control the average LED current and reach flicker compensation. An average inductor current control method allows wide range of LED voltage and high accurate LED current. In addition, a floating ground topology is used to drive the power MOSFET directly and to simplify the circuit. Finally, the results of experiments show that low-frequency current ripple and no light flicker issue from AC line frequency can be solved by the two-stage power topology. This thesis not only contains the working theory and design method of the circuit in detail but also proves it by the result of experiments.